Change host provider

From an MVP perspective [Heroku](http://heroku.com/) is an easy way to deploy application and I think for a first step we should deploy with it.

Howerver there are some limitation using Heroku with Elixir/Phoenix (https://hexdocs.pm/phoenix/heroku.html#limitations):

So when the app will be used by more users we might need to find an alternative, [AWS](https://aws.amazon.com/), [DigitalOcean](https://www.digitalocean.com/), [Gigalixir](https://gigalixir.com/)?

The issue names no files, tests, or deployment entry point. Start by reviewing the existing Heroku deployment and the linked Phoenix Heroku limitations, then compare AWS, DigitalOcean, and Gigalixir for the expected growth. Done means an alternative provider is selected and the deployment scope is agreed.

Escrito por el modelo de indexación a partir del texto del issue.